Many forms of brakes for bending sheet materials or the like are known. In general, there is provided a base of suitable type to which the sheet metal is clamped by a clamping jaw having an edge against which the metal is bent. The workpiece is clamped between the anvil jaw and the base, and a bending leaf is pivotally attached to the base adjacent and beneath the clamping jaw edge. As the bending leaf is raised, the bending leaf contacts the workpiece to bend the metal upwardly about the front edge of the clamping jaw.
The prior art may be exemplified by such patents as U.S. Pat. No. 3,592,037 granted to Van Cleave, July 13, 1971 for "Sheet Metal Bending Brake"; U.S. Pat. No. 4,092,481 to Chambers, Jr., on June 6, 1978 for "Sheet Metal Brake"; U.S. Pat. No. 3,147,791 to Rauen et al., on Sept. 8, 1964 for "Brake for Bending Sheet Metal"; and my U.S. Pat. No. 4,081,987 granted on Apr. 4, 1978, for "Wide-Range Sheet Material Bending Brake".
As illustrated in these and other patents it has been customary heretofore to use a piano type hinge which acts as a bearing for the bending leaf. In the forms exemplified above, the piano hinge or bearing is exposed to dirt. Furthermore, this form of bearing requires a pin for attaching the bending leaf to the base or frame of the brake. Even where the hinge elements are integral with the bending leaf and the base, the formation of the interdigited hinge projections and the insertion of the hinge pin requires milling of the hinge elements, cleaning of the pin holes, etc.